When the bacterium Serratia marcescens is grown on a sterile culture medium in a petri dish at 30°C, the bacterial colonies are cream colored. When this same bacterium is cultured under identical conditions, except at a temperature of 25°C, the colonies are brick red. This difference in color is most likely due to the
1
type of nutrients in the culture medium
2
sterilization of the culture medium
3
effect of temperature on the expression of the gene for color
4
effect of colony size on the synthesis of color pigments

What is histamine and what is its role in allergic reactions

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What is the difference between the conducting zone and the respiratory zone of the respiratory system? the conducting zone is a series of cavities and tubes that move air to the respiratory zone where gases exchange with the bloodstream. the conducting zone exchanges gases between the lungs and the alveoli and the respiratory zone is a series of cavities and tubes that move air to the conducting zone. the conducting zone moves oxygen into the cells and the respiratory zone takes carbon dioxide away from the cells. the conducting zone moves oxygen into the bloodstream and the respiratory zone takes carbon dioxide away from the bloodstream.